Flushing the toilet is such an automatic part of daily life that most of us rarely stop to consider what happens afterward. Every flush sends clean, treated water into the sewer system, and depending on the toilet, a single flush can use several liters. With toilets being flushed multiple times each day, the amount of water used by one household can become surprisingly large over the course of a year.

That has led some people to rethink how often they flush. One familiar approach is the saying, “If it’s yellow, let it mellow; if it’s brown, flush it down.” The idea is simple: avoid unnecessary flushes when possible. While some people may worry about odors or hygiene, regular cleaning and good bathroom ventilation can help. But if you’re not comfortable with that approach, there are other ways to reduce water consumption. And one surprisingly simple change can make a meaningful difference…